Quantitation reference compounds and VOC recoveries from soils by purge-and-trap GC/MS

Unquantified volatile organic compound (VOC) losses occur in every phase of VOC determination including sample collection, transport, storage, preparation, and analysis. Current quality assurance/quality control measures, such as surrogate spikes and internal standards, do not account for losses that occur during sample handling nor do they account for soil matrix effects. An alternate approach, the quantitation reference compound (QRC) approach, is presented that involves direction injection of the QRCs onto the soil matrix to account for any matrix effects and losses during subsequent processing steps prior to sample analysis. Final VOC quantitation is based on the QRC instead of the internal standard, which is used strictly to monitor instrument performance. Quantifying VOCs using the QRC approach on three spiked performance evaluation soils and one unprocessed spiked field soil resulted in target compound relative recoveries of 93-105%. In contrast, using the current quantitation approach, target compound recoveries were only 2-27%. Precision between the two approaches was equivalent (on an absolute basis) with relative standard deviations of 2-15% using the QRC approach.